Gas turbine engines may be used in industrial applications, such as, but not limited to, oil and natural gas transmission, gathering, storage, withdrawal, and lifting. In these applications, turbine engines are often located in offshore or remote locations, and it is very costly for customers to ship the engines off-site to the manufacturer for maintenance and/or repairs. Particularly, customers incur expenses in terms of shipment and maintenance or repair costs, as well as production down-time. Accordingly, it would be advantageous to enable on-site repairs and maintenance by the turbine engine manufacturers, especially in remote or off-shore customer locations.
The conventional construction of turbine engines, however, does not facilitate on-site maintenance or repairs, particularly because components of the engine most susceptible to wear—and therefore, failure—are embedded within the casing of the engine. Therefore, these components cannot be accessed without disassembling at least a significant portion of the engine, which is usually not feasible on a customer site for a variety of reasons. For example, an offshore oil platform may have space constraints that are not conducive to disassembly. Additionally, it may be difficult and/or expensive for the manufacturer to bring certain tools required for disassembling the engine to the customer site; or the space constraints imposed by the customer site may preclude bringing such tools. Additionally, turbine engines are often assembled and disassembled vertically in the factory. In the field, however, the engines are commonly arranged horizontally, which makes disassembly cumbersome. Thus, for at least these reasons, turbine engines must often be shipped off-site to the manufacturer for repairs and maintenance, which is inefficient and expensive.
Turbine engines generally comprise a plurality of rotating airfoils within a casing that drive (rotate) an axial shaft that extends longitudinally through the center of the engine. The shaft usually protrudes from the engine casing, and is used to drive subsequent components and/or systems, such as pumps, etc. Additionally, an accessory drive gearbox can be coupled to a protruding portion of the shaft via a coupling shaft.
The accessory drive gear box may have one or more gears and may be used to provide power to auxiliary systems such as generators, alternators, air conditioning systems, pneumatic systems, hydraulic systems, or the like. Also coupled to the protruding portion of the shaft may be, among other things, a bearing assembly for mounting the shaft to the engine and supporting both radial loads and axial thrust loads from the shaft; a thrust collar for transferring the axial load to the bearing assembly; and a forward air/oil seal, which seals lubricant, such as oil, within the bearing assembly and prevents the oil from infiltrating the compressor. The components of a turbine engine that can be among the most susceptible to wear and failure include the bearing assembly, the thrust collar, and the forward air/oil seal.
Various seal designs have been developed for the air/oil barrier between bearing compartments and compressor compartments. For example, U.S. Pat. No. 6,330,790 to Arora et al. (hereinafter “the '790 patent”) discloses a labyrinth seal between a bearing compartment and a compressor compartment. However, extensive disassembly of this engine is required for removal of the seal. In this configuration, in order to remove the abradable (i.e., wearable) portion of the seal, the air intake housing must be removed because the seal is larger than the opening in the air intake housing and is located aft of that opening. Such extensive disassembly makes repair/replacement of the seal impractical to carry out in the field. Therefore, the engine must be transported to a repair site equipped with specialized, large-scale equipment designed to support and remove large components like the air intake housing. It is also noteworthy that, in some systems, as in the '790 patent, the forward seal is actually two separate seals. Often these separate seals have different diameters, i.e., in a stepped configuration. Designs with two separate seals can be more expensive (i.e., simply because there is an additional part) and even more difficult/costly to service (i.e., because more engine disassembly may be required to remove both seals).
In addition, some turbine engine manufacturers have developed systems in which the protruding shaft extends through, and sometimes beyond, the air inlet housing and is supported with a bearing assembly that is supported by a separate bearing housing, which may be fastened to the air intake housing. In such configurations, the bearing assembly may be accessed without removing the air intake housing from the engine. However, supporting the bearing assembly with a separate bearing housing can be a less robust design than supporting the bearing assembly with the air intake housing, which is typically a large, rugged structure. Therefore, systems with these configurations often sacrifice the robustness of the shaft support in order to produce an engine that is more easily serviced.
The present disclosure is directed toward overcoming one or more of the problems discussed above.